ABSTRACT
Cooling Characteristics of a Heat Sink for LED Headlight
used in Passenger Cars

Yu, Jae Yong
Advisor : Prof. Yang, Seemoon
Department of Automotive Engineering
GraduateSchoolofIndustrial Technology


Heat sinks are the commonly used devices for enhancing heat transfer in electronic components. An optimal of design of heat sinks is influenced by various geometrical parameters such as fin length, fin thickness, number of fins, base plate thickness, space between fins, fin shape etc. Also, the design of an optimal heat sink requires a complete knowledge of all heat transfer characteristics between the heat source and the ambient air and thus it is essential to fully understand the effects of given boundary conditions such as applied heat fluxes and approach air velocities on cooling characteristics of the heat sink. The objective of this thesis is to investigate the cooling characteristics of a heat sink for LED headlight used in passenger cars. To this end, this thesis deals with the experimental and numerical analysis of the heat sink heated at constant heat fluxes with/without air flow applied.
In the experiments, heat was transferred at a constant heat flux (ranging from 9974 W/m2 to 16860 W/m2) through the bottom of a heat sink for natural convection mode. For forced convection mode, the bottom of the heat sink was heated at fixed heat flux of 16860 W/m2 while air flow velocity ranging from 2m/s to 6m/s was applied around the heat sink. Measured temperature on pre-selected locations of the heat sink was in good agrement with numerically predicted one. Experimental and numerical results indicate that the convective heat transfer coefficient for natural convection mode was decreased with increasing the heat flux applied to the bottom of heat sink, lowering the cooling capabilities. On the other hand, the convective heat transfer coefficient was found to significantly increase with air flow velocities, enhancing the cooling capabilities.